Influence patterns and remedial measures of uneven settlement of column footings on single diagonal bracing steel derrick
Long-term load effects may cause deformation and uneven settlement of the mine derrick,and even leading to collapse of the structure.According to the settlement and stress characteristics of a steel structure single diagonal bracing derrick in Tongting Coal Mine,the structural model of the single diagonal bracing derrick was constructed with ANSYS.Influence law of the uneven settlement of the inclined brace foundation on the internal force of the derrick structure was studied,and the mechanism of the influence of the uneven settlement on the internal force of the derrick was analyzed.The results show that:① The settlement difference between the vertical frame and the inclined brace will cause a linear increase in the stress of column C and top beams of the vertical frame,and has little effect on the inclined brace.When the settlement rate in the X direction reaches 2.4‰,the maximum stress of the vertical frame appears at the bottom of column C with a value of 148 MPa,which is below the permissible design strength limit for the steel material.②The stress overrun failure occurs when the settlement rate in Y direction under the condition of rope breaking is 0.88‰,which is slightly lower than the maximum settlement difference limit of 1‰ stipulated in Standard for Design of the Mine Headframes.③The uneven settlement leads to a redistribution of internal forces in the derrick structure.The maximum stress and displacement of the derrick increase with the increase of the settlement value,and the column C of the vertical frame and the upper and lower head sheave beams of the inclined brace are identified as the most dangerous parts.In response to the current situation of the subsidence of the derrick,reinforcement and jacking plans for key parts was proposed.After reinforcement,the static performance of the derrick was enhanced by 30%with a significant reduction for the internal force and deformation.
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